Backlight modules have been applied extensively to everyday lives. In particular, they can almost be found in digital devices such as regular cellular phones, personal digital assistants (PDAs), as well as in MP3 (MPEG Audio Layer3) players. The backlight modules of such digital devices are usually affected by electromagnetic interference (EMI), resulting in frame jitters. EMI is the interference of electromagnetic noises or unnecessary signals for devices and are generated by the operation of apparatus or devices containing electronic components. By means of radiation or conduction, other devices will be affected, and consequently abnormal operations will result.
Furthermore, the backlight modules will be damaged caused by electrostatic discharge (ESD). In everyday lives, it is normal to generate static charges by rubbing. After rubbing two insulating surfaces against each other and separating them, ESD will occur. ESD will damage integrated circuits (ICs) of the backlight modules, and will cause light-emitting diodes (LEDs) or cold cathode fluorescent lamps (CCFLs) of the backlight modules malfunction. Thereby, it is necessary to use many conducting materials, such as iron housings, sheets of copper or aluminum foil, or sheets of conducting polymer. By connecting the conducting materials with the ground of the device, the backlight modules can be free from EMI and ESD.
FIG. 1A is a three-dimensional view of a backlight module according to the prior art. As shown in the figure, the backlight module in the prior art uses a metal housing 10 to cover the backlight module, and connects the metal housing 10 to the ground of the system (ex. Cell-phone/PDA, etc.). Thereby, by means of the installed metal housing 10, the backlight module can avoid EMI and thus can operate normally. In addition, static charges can be led to the ground of the system. As a result, The ICs, LEDs, or CCFLs devices of the backlight module can be protected from the damages due to ESD. Moreover, the metal housing 10 not only can avoid EMI or ESD, it also can be a reflector or a reflecting cover of the backlight module at the same time. Nevertheless, installing the metal housing 10 will increase the thickness of the assembled backlight module. For modern digital devices such as cellular phones or PDAs, the volume of the devices tends to be compact. Consequently, there is no spare space to accommodate the metal housing 10. Besides, the manufacturing cost will be increased by installing the metal housing 10.
FIG. 1B is a three-dimensional view of another backlight module according to the prior art. As shown in the figure, in order to prevent the backlight module from abnormal operations due to EMI and ESD on the condition that the assembled thickness of the backlight module cannot be increased, a circuit 20 of the backlight module is covered by a sheet of aluminum foil, and a reflector 40 is installed on the backlight module to reflect lights from the backlight module. In addition, the sheet of aluminum foil 30 is connected to the ground such that the ICs, LEDs, or CCFLs of the circuit 20 are protected by the sheet of aluminum foil. By replacing the metal housing 10 with the sheet of aluminum foil 30 and the reflector 40, the problem of thickness increase as a result of installing the metal housing 10 on the backlight module can be avoided.
When a backlight module is subject to EMI or ESD, EMI is prevented by the sheet of foil while ESD is prevented by conducting static charges to the system ground. However, because it is necessary to cover additionally the sheet of aluminum foil 30, the assembly steps will be increased, which means an increase of assembly time, reducing the throughput of manufacturing the backlight module. If the damages caused by EMI and ESD on the backlight module can be avoided while reducing the assembly steps, the throughput of manufacturing the backlight module can be increased.
Accordingly, the present invention provides a reflector that can prevent the backlight module from damages caused by EMI and ESD, as well as reducing assembly steps of the backlight module. Thereby, the throughput of manufacturing the backlight module is increased, solving the problems described above.